A graphics processing unit (GPU) is typically a dedicated graphics rendering device for a personal computer, workstation, game console, mobile computing device, such as a smart phone, PDA, or other hand-held computing device, or other video hardware. A GPU can be integrated directly into the motherboard of the device or the GPU can reside within an individual video card coupled to said motherboard, as an external GPU. Many computers have integrated GPUs, which can be less powerful than their add-in counterparts, external GPUs. A user seeking high performance graphics, for example, for a video game, will often add an external GPU to a system with an existing, integrated GPU. Additionally, processing units such as central processing units (CPUs) or cores of a multi-core CPU can be enabled to render graphics.
Adding an external GPU may override the functionality of an integrated GPU. Alternatively, two or more GPUs can share the workload of rendering an image for a display: two identical graphics cards are coupled to a motherboard and set up in a master-slave configuration. The two GPUs then split the workload by either dividing the content of the display or rendering alternate frames. In dividing the content of the display, the slave GPU may render a portion of the screen and transmit it to the master GPU. In the meantime, the master GPU renders the remaining portion of the screen and combines it with the rendered portion from the slave GPU before transmitting it to the display device.
As the processing power and the number of GPUs within a system has increased, so has the demand for electrical power. Many applications do not require the processing power of an external GPU. Additionally, a user may want to conserve power, for example, when operating a device on a battery, and be willing to sacrifice some GPU processing power in exchange for energy savings. In view of aforementioned, it is desirable to have an apparatus, system, or method to migrate a display from a first GPU to a second GPU and reduce the power drawn by the first GPU while it is not in use. It is further desirable to migrate the display seamlessly and without substantially interrupting the display stream to the display device.